The Milky Way’s core may be dense dark matter, not a black hole

For decades, scientists have theorized that the Milky Way Galaxy’s supermassive black hole, known as Sagittarius A* (Sgr A*), ...
IEEE

Optimal phase angle design for the lunar lander

Abstract: To design the optimal lunar landing trajectory, the periapsis of de-orbit burn phase is usually used as a starting point of the powered descent phase. And the optimal problem is constructed ...